In recent years, there has been an increase in the number of vehicles equipped with an electric power steering system (hereinafter called the “EPS”). The EPS uses an electric motor to provide steering assist to a driver of a vehicle. The motor is controlled by an electronic control apparatus mounted on the vehicle.
For example, the electronic control apparatus is mounted near a steering column shaft. In this case, liquid such as interior cleaning fluid or water due condensation in the column shaft may drip on the electronic control apparatus. The liquid may enter the electronic control apparatus through a clearance between a lid and a housing of the electronic control apparatus and cause the EPS to go down. US 2007/0230137 corresponding to JP 2007-273807A discloses one method for preventing such a problem. In US 2007/0230137, the clearance is filled with a sealing material so that the inside of the electronic control apparatus can be sealed.
In another method, the electronic control apparatus may be wrapped in waterproof sheet that can prevent liquid from entering the electronic control apparatus. However, using a sealing material or using a water proof sheet can increase manufacturing cost and complicate manufacturing process.